Triple glazing can improve centre-pane thermal performance, but it is heavier and more expensive. The right choice depends on the whole rooflight value, orientation, glass area, solar control, supporting structure and project energy strategy.
When triple glazing helps
Triple glazing can reduce heat loss and improve internal surface temperatures where a stronger thermal specification is required. It may be useful on new-build or high-performance projects.
The improvement should be checked using horizontal or sloped performance data rather than a vertical-window value.
Why double glazing may still suit
A well-specified double-glazed rooflight may satisfy the project target with lower weight and a simpler installation. Solar-control coatings can be more important than adding a third pane on strongly exposed roofs.
Larger or complex units also need lifting, frame capacity and supporting structure to be considered before glass thickness is fixed.
Project checklist
More panes do not automatically create the best rooflight. Balance heat loss, daylight, solar gain, weight and cost for the room and building.
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